CSAT on the first day; 2 interviews on the second day
Don't worry if the test seems difficult; on interview seemed better than the other.
Use Cambridge departmental webpages; ask your teachers for help.
Don't overthink the process and relax.
Remember this advice isn't official. There is no guarantee it will reflect your experience because university applications can change between years. Check the official Cambridge and Oxford websites for more accurate information on this year's application format and the required tests.
Also, someone else's experience may not reflect your own. Most interviews are more like conversations than tests and like, any conversation, they are quite interactive.
The first interview was a maths-based problem that started out simple and gradually got more complex and abstract as certain rules changed and developed. The second interview was just discussing and showing how to solve the problem.
The second interview started similarly with a problem-solving task but it was less maths-based, and then we talked about my interests and things mentioned in my personal statement; I enjoyed this interview a lot more.
Using the Cambridge computer science department website for sample CSAT papers and information, and
By the time I got to my final interview I had pretty much given up hope of getting an offer because I thought the others had gone so badly, I was very relaxed and not nervous anymore which actually really helped - some advice is try not to overthink it and just relax.